Transmission gearing



Jan. 31, 1950 w. SHEPPARD 2,495,988

TRANSMISSION GEARING Filed July 14, 1943 2 Sheets-Sheet 1 In verez a r2 Ida/2456:2721 .Z. Jig yard Jan. 31, 1950 w. L. SHEPPARD 2,495,988

TRANSMISSION GEARING Filed July 14, 1943 2 Sheets-Sheet 2 Patented Jan. 31, 1950 TRANSMISSION GEARING William L. Sheppard, Royal Oak, Mich., asslgnor to Borg-Warner Corporation, Chicago, Ill., a

corporation of Illinois Application July 14, 1943, Serial No. 194,619

7 Claims.

This invention relates to transmissions of the gear type and particularly to transmissions in which the axis of rotation is disposed vertically as for example in transmissions for driving the main rotor blades of a helicopter.

It has been proposed in one form of transmission for a helicopter to disconnect the transmission from the prime mover by means of a clutch so that the engine could be tested without operating the sustaining rotor of the helicopter. The clutch is manually operated and is enclosed in a separate housing removed from the transmission.

One of the objects of this transmission is to simplify and lighten the transmission and clutch by incorporating the clutch in the transmission housing. Another object of the invention is to provide power means for operating the clutch, with automatic control means for the power means.

It has also been proposed in a helicopter to utilize a construction wherein the main rotor is automatically disconnected from the clutch by means of a one-way clutching device so that should the engine fail, the main rotor would still be effective to support the helicopter and thereby permit a gradual descent to the ground without power. The helicopter under consideration is also provided with a vertical tail rotor for controlling its lateral movement, this tail rotor being driven from the same engine and preferably at a reduced speed. Under a, dead engine condition it is desirable that the tail rotor be operated simultaneously with the main rotor so as to provide better control during the descent. In the prior transmission, therefore, the one-way device is inserted between the transmission proper and the clutch so that the entire transmission must be driven by the rotor when the engine fails. This condition is not always desirable since, if the transmission is not functioning properly due to a burned out bearing or other mechanical failure, it is not possible to permit the rotors to turn without simultaneously operating the wrecked transmission.

Thus another object of this invention is to provide a one-way connection between the tail rotor and the transmission, the tail rotor bein driven directly from the main rotor shaft.

Another and more specific object of this invention is to provide an alternative, simpler power take-off mechanism for driving the tail rotor of a helicopter.

These and other objects of the invention will become apparent from the following detailed description when taken together with the accompanying drawings in which:

Fig. 1 is an elevation in section of a transmission incorporating the above-described improved construction; and

Fig. 2 is a fragmentary elevation in section taken through the alternative form of tail rotor take-oil mechanism.

Referring now to Fig. 1 for a more detailed description of the invention, Ill is a housing preferably made of light-weight metal such as magnesium or aluminum and secured in a suitable fashion to the frame-work of the helicopter or other device in which the transmission is operated. Said housing has a pair of bearings l I and I2 concentrically disposed at opposite ends thereof. A drive shaft I3 is supported in bearing ll and a driven shaft I4 is supported in bearing l2. Drive shaft l3 may be connected by means of the splined flange l5 directly or indirectly to the drive shaft of the prime mover. Driven shaft I 4 may be connected to the main rotor of a helicopter, either directly or through a suitable pitch controlling mechanism (not shown). It is necessary that a speed reduction and torque multiplication of about 11-1 be provided between drive shaft i3 and driven shaft it. This speed reduction is effected in the transmission shown, by means of reduction gearing designated generally by reference character l6.

Said transmission I6 is comprised of a drive pinion ll formed on one end of a sleeve l8 which is loosely mounted on drive shaft l3, said pinion i1 meshing with a plurality of countershaft gears l9 and 20 rotatably mounted on countershafts 2| and 22, respectively, fixed in housing ill. The use of a plurality of countershafts reduces the tooth loading on the gears and permits the use of smaller and hence lighter gears. It also results in a balanced or symmetrical design which simplifies the construction of housing I0 and also the lubrication problems. Said countershaft gears l9 and 2!] drive smaller oountershaft gears 23 and 24 respectively, both of which mesh with an in ternal gear 25. Said internal gear 25 is connected by means of a one-way drive device 26 to output shaft ll.

Drive shaft i3 is connected to sleeve it through a multiple disc friction clutch 21, the clutch comprising a drum 28 rotated with drive shaft l3 and having internal splines 29 which drive a plurality of friction plates 39 axially slidable along splines 29. Between driving plates 30 are located the driven plates 3| which are splined to sleeve l8 so as to be rotatable therewith. Operating pressure is supplied by a pressure plate 32 which may be in the form of an annulus and which operates in a cases 3 correspondingly annular chamber 83 formed in drum 28. An annular piston 34 likewise operates in chamber 33 and is directly contacted by oil under pressure supplied to chamber 33 by means hereinafter to be described. The reaction for the operat ng pressure is supplied by plate 33 likewise driven by splines 28 and restrained from axial movement along the splines in an upward direction by a snap ring 38.

One-way clutch 26 is comprised of a flange tl spaced from and driven by ring gear 25, and preferably made integral therewith, said flange 31 being formed with axially extending teeth 34 whlch mesh with similarly axially extending teeth 39 on a sleeve 40. The normal direction of rotation of ring gear is indicated by the arrow and the ends of teeth 38 and 39 are chamfered as shown so as to facilitate engagement of the teeth when the relative direction of rotation between the teeth is such that ring gear 25 tends to drive sleeve 40 and to prevent engagement of the sleeve when the relative direction of rotation is reversed. that is, when sleeve 40 tends to rotate ahead of ring gear 25. A spring serves to maintain teeth 39 in contact with teeth 33 when the former are rotat ng faster than the latter. Sleeve 4|) is formed with internal helical splines 4| which mesh with external helical splines 42 formed on driven shaft I4. Two snap rings 43 and 44 limit the downward and upward travel, respectively, of

sleeve 4t along sleeve 42.

It will be apparent from the direction of the helical splines that if output shaft II should tend to continue rotating after ring gear 23 has slowed down or stopped, sleeve 40 will move axially upward on splines 42 until teeth 39 are free of teeth 33, and then the entire sleeve will rotate on shaft l4 relative to teeth 38. Just prior to the complete disengagement of teeth 39, spring 45 is compressed so that upon disengagement of teeth 39, the chamfered ends of both sets of teeth will ratchet over one another. when output shaft 14 slows down below the speed of gear 25, or is overtaken by gear 25, the ratcheting teeth will catch and the helical spline will then complete the engagement of the clutch. Thus clutch 26 drives only when ring gear 25 tends to rotate ahead of output shaft i4 and therefore functions as a positive one-way clutch.

Also drivingly connected to splines 42 is bevel gear 46 which meshes with a bevel pinion gear 41 on an output shaft 41a. arranged at an angle to the input shaft, for driving the tail rotor (not shown) of the helicopter, or other apparatus the function of which is related to the rotation of main rotor. It will be observed that pinion 41 rotates with bevel gear 46 and output shaft H whenever the latter is rotating whether powerdrlven through gears It or rotating solely under the acre-dynamic influence of the main rotor.

Oil under pressure for operating clutch 21 and for lubricating the one-way clutch and the transmission is supplied by a pump 48 which may be of anywell known type, and for purposes of illustration is shown as a gear type pump having a pinion gear 49 driven by shaft [3 and meshing with a ring gear 50 loosely mounted in a pump housing 5|. Said pinion gear 49 has one tooth less than gear 50 and the shape of the gear teeth is such that a seal is formed at all times between the input and output sides of the pump. It will be noted that the pump is located at the lowermost point in the transmission and actually is below the normal level of the oil in housing It. The oil is pumped from the sump 52 through a filter It to the input passageway 84 of pump 43 and then through the pump to the output side 53 whence it flows in two paths, one path 56 leading to the hollow portion 51 of input shaft II and the other 53 leading to an annular chamber 69. From chamber 59 oil is fed by passageways Ill and ii to the hollow countershai'ts 22 and 2|, respectively, through radial bores 32 to the outside of shaft 22 and thence through openings Iii to the gear teeth and other portions of transmission It. In passing between the gears and their shafts Ii and 22 to the openings 83 the flow of oil is materially restricted to permit the pressure to build up in chamber 59 and in hollow portion 51 of shaft l3.

Chamber I1 is closed off by means of a plug 34 having an opening therein, the opening being closed by a plate 66 held thereagainst by a spring 31. Said plug 64 is provided at its outer end with an apertured plate 68 against which spring 61 bears. The tension in spring 31 is sullicient to cause a predetermined clutch-operating pressure to be built up in chamber 81 but will yield to higher pressures and allow the excess oil to pass through opening 65. The pressure so developed is transmitted through a conduit 89 to chamber 33 in drum 28 and thence through an opening it to a valve chamber H in which is a radially movable valve 12 adapted to close off opening 10 when drum 2! is rotated at a predetermined speed. A spring it normally keeps valve I2 in its radially inward position so as to allow the oil to escape from chamber 33 through port 10 and through a corresponding opening 14 into sump 52. It will be apparent that as long as valve I2 is in the position shown, no pressure can be built up in chambers 51 and 33 and hence clutch 21 will be inoperative. When drum 28 is rotated at or above the critical speed for which valve I2 is set. the valve will move outward, thus closing ofl. opening II and permitting clutch operating pressure to be built up, the excess pressure as described above being relieved through opening in plug 64.

In order to enable the operator to test the engine without engaging clutch 21, a manually operated valve 15 is provided in conduit 60, said valve being adapted to dump the oil in this conduit and therefore in chambers 51 and 59. In the position shown, the valve permits oil under pressure to flow into hollow countershaft 22 and does not destroy the pressure in the system. When valve 15 is made to assume its right hand position (Fig. 1) the how oi oil is cut oi! from the upper portion of conduit and it passes around valve 15 into a dump port I8 whence it falls into the sump 52. Dump port 16 is sufllciently large to prevent any building up of pressure in chamber 51 so that should the engine be operated and input shaft l3 rotated at the speed at which valve 12 closes the port ill, there will not be sumcient pressure built up in the system to operate clutch One-way device 28 is lubricated by means of oil passing through plug 64 into chamber 8| in output shaft l4 and then into a side opening 82 and an oblique opening 83 from which point it ultimately flows into a chamber 84 formed by flange 31, output shaft l4, bevel gear 46 and a stamping 85 which connects the outer portion of bevel gear 46 with flange 31. Thus sleeve 40 operates in a chamber full of lubricant at all times, except of course, when plate 56 prevents tshe oil from passing through opening 65 in slot Under some circumstances the disconnecting function of the one-way device 29 may be performed by centrifugaliy controlled valv 12 and by the manually controlled valve 15. At low engine speeds, for example, clutch I1 is automatically disengaged by valve I2 and output shaft II is thus free to turn. At high engine speeds, valve 15 may be operated to again release clutch 21 and free output shaft I4. The oneway device might therefore be eliminated and shaft It could be directly connected to ring gear 18. A transmission so modified is disclosed in Fig. 2 as is also a modified power take-off mechanism which is somewhat lighter in weight for the same capacity, than the one disclosed in Fig. 1.

Referring now to Fig. 2 the drive shaft is shown at 99 driving a pump 91 and a clutch 99 which may be identical with clutch 21 in Fig. 1. Clutch .9 drives a sleeve 99 on which is formed a gear second being shown at 99 and meshing with a ring gear 95 which is directly connected to an output shaft 96 for driving the main rotor of a helicopter.

Countershaft gear 9| has formed integral therewith a beveled gear 99 which meshes with i a beveled pinion 99 rotatable about an axis which may be at right angles to the axis of rotation of bevel gear 99. Said bevel gear 99 drives a shaft I99 which in turn may be connected to the tail rotor or other mechanism of the helicopter. Suitable bearings IIII, bearing retainers I92 and fasteners I93 may be used to support shaft I99 and gear 99 in housing 93.

The lubricating system for the transmission shown may be modified so that lubricant from the chamber I95 communicating with the high pressure side of the pump is conducted through a pipe I94 to hollow countershaft 92 and through a side opening I99 into a drilled passageway I91 in a threaded plug I99, the passageway I91 communicating with a chamber I99 in a support H9 for beveled pinion 99.

It is understood that in Fig. 2 clutch B9 is automatically operated by the some means shown in connection with clutch 21 in Fig. 1 and that a manually operated valve similar to valve I9 of Fig. 1 is used on the opposite side of pump 91. These two devices can render the gearing independent of drive shaft 99 so that should the engine stall while the helicopter is in the air it could be disconnected from the rotors and the latter could then operate to support the helicopter while it descended to the ground. It will be observed that beveled pinion 99 is meshed with beveled gear 98 which in turn is rotatable with countershaft gear 94 meshed with ring gear 95. It will thus be observed that the tail rotor driven from shaft I99 will always rotate when the main rotor driven from shaft 99 is rotated and hence full control of the helicopter may be had even though there is a power failure.

In both forms of power take-oil. it is understood that in addition to driving th tail rotor, the power take-01f may also drive other auxiliary apparatus such as the tachometers, governors, electric generators, etc., the continuous operation of which during flight is highly desirable, or that the take-on may drive such auxiliary apparatus exclusively, the tail rotor being driven by some other source of power.

It is understood that the foregoing description is merely illustrative of preferred embodiments of the invention and the scope of the invention therefore is not to be limited thereto but determined by the appended claims.

I claim:

1. In a helicopter, a transmission for driving the sustaining rotor thereof. comprising a housing. input and output shaftsextending into the h using. gearing in the housing for providing a torque multiplication between the input and output shafts, an oil-operated clutch connecting the input shaft to the gearing. one-way positive clutch means for connecting the gearing to the output shaft. an oil reservoir surrounding the one-way clutch means, a second 011 reservoir supplying oil under pressure to th oil-operated clutch, and a pressure relief valve limiting the pressure in the second reservoir, the oil escaping through the relief valve being conducted to the first reservoir such that the first reservoir is not filled until after clutch operating pressure is established in the second reservoir.

2. A transmission for driving the sustaining rotor of a helicopter as described in claim 1, including a power take-off driven by the output shaft, said power takeoff defining a part of the first reservoir.

3. A transmission for driving the sustaining rotor of a helicopter as described in claim 1, and a valve in hydraulic communication with the second reservoir and responsive to the speed of the input shaft for dumping the pressure in the second reservoir when the input shaft is rotated at low speed.

4. In a helicopter, power transmitting means comprising an input shaft, an output shaft, a second output shaft connected to the first output shaft and driven thereby, and a one-way clutch mechanism connected between the input shaft and said first output shaft, said clutch mechanism including a toothed member connected with the input shaft, a helically splined member connected with the output shaft, and an axially shiftabie member having helical splines meshing with the splines on said helically splined member and having teeth which mesh with said toothed member when the toothed member rotates faster than the helically splined member.

5. In a helicopter, power transmitting means comprising an input shaft, an output shaft, reduction gearing operatively disposed between said shafts and a one-way clutch means drivingly connected in series between said shafts, said clutch means including a toothed member connected with a reduction gearing, a helically splined member connected with one of the shafts, and a shiftable collar having helical splines meshing with the splines on said helically splined member and having teeth which mesh with said toothed member when the input shaft is the driver.

6. In a helicopter, a housing, input and out ut shafts extending into the housing, gearing within the housing for providing a torque multiplication between the input and output shafts, a clutch within the housing automatically connecting the input shaft to the gearing in response to predetermined speeds of the input shaft, and a one-way clutch drivingly connected in series between said shafts and including a. toothed member connected with said gearing, a helically splined member connected with one of the shafts, and a shiftable collar having helical splines meshing with the splines on said helically splined 7 member and having teeth vlhich mesh with acid toothed member when th input shaft is the driver.

7. Power transmitting means for a helicopter as described in claim 6 wherein the ends of the teeth on the collar and on the toothed member are chamfered to prevent engagement of said teeth until the collar and toothed member are substantially synchronized, and resilient means !or causing the chnmfered ends of the teeth to engage when the output shaft is the driver.

WILLIAM L. SHEPPARD.

REFERENCES CITED The following references are of record in the file of this potent:

UNITED STATES PATENTS Number Name Dnte 968,860 Bummer Aug. 30, 1910 1,052,986 Tucker Feb. 11, 1913 1,898,951 Holland Nov. 22, 1932 Number Number 387,900 491,513

8 Name mm Simpson et a1. Feb. 27. 1934 Bnnnan Mar. 8, 1934 DAncanio May 22, 1934 Von Boden- Fraunhofen et 2.1. Aug. 27, 1935 Platt Mar. 23, 1937 Sneed June 29, 1938 Gerhardt Nov. 1, 1938 Pecker Feb. 4, 1941 Giiiord et a1. June 23, 1942 Frudden Apr. 27, 1943 Sikorsky May 4, 1943 Woods Jan. 25, 1944 Shavinsky Oct. 2, 1945 Fedden et a1. Nov. 27, 1945 FOREIGN PATENTS Country Date Great Britain Feb. 16, 1933 Great Britain Sept. 5, 1988 

